[Xcb] X server bug on BIG-REQUESTS?

[Jamey Sharp]

On Sat, Jun 10, 2006 at 10:26:46AM -0700, Barton C Massey wrote:
> Betcha $1 it's an ancient server bug.

I want to be on Bart's side for this bet. I'd even be willing
to up the stakes except I don't actually want to separate Ian
from his money. :-)

> Until we get it diagnosed and fixed, I vote we work around
> it by setting the limit on request size for this request to
> 1MB rather than 4MB.

I'm not sure exactly what you mean by this. We can have
XCBGetMaximumRequestLength divide the value returned from
BigRequestsEnable by four, which seems likely to work on all
servers. There's a separate problem that callers, including
the XCBImage library, need to split large data into smaller
chunks.

> This will be invisible on servers with BIGREQUEST (i.e. most
> of them), and mostly invisible even on servers without.

I don't understand this at all.

> Once we have the putative server bug diagnosed and fixed,
> we'll have a harder decision; I suspect we should check the
> server version and continue to go small on old servers.

That seems reasonable.

> Has someone checked other requests that send large data to
> see if they also cause the problem?  If it's in the
> server-side handler, it's likely this isn't the only broken
> request.

Someone could take my code and make it use ChangeProperty with
a million format=32 list elements. Any takers?

--Jamey
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